The Flow Cytometry and Cell Sorting Facility was established by the Cancer Center in 1980. It has been continuously approved and funded by the NCI Core Support Grant since 1981. Jonni Moore, PhD, has directed the Flow Cytometry and Cell Sorting Facility since 1990. Dr. Moore has a doctorate in immunology and over fifteen years of flow cytometry experience, and serves as an expert consultant to manufacturers of flow cytometry equipment (i.e., Becton Dickinson) and to other flow cytometry laboratories (e.g., SmithKline Beecham, Merck). Charles Pletcher, MCI, Technical Director has been with the Facility since 1987. The Facility has grown tremendously during the current project period. This has resulted from major operational improvements, during acquisition of newer technology, and recruitment of expert staff. With the equipment purchased during the current project period (FACSVantage and FACSCalibur), it now possesses capabilities equal to those of the most sophisticated flow cytometry facilities. Overall usage of the core has increased 67% during the current project period. Usage by Cancer Center members with peer-reviewed funding is 77% and usage by all Cancer Center members is 86% of total facility usage.